Multi-cabinet ends in filamentary yarn processing equipment must have some means of indicating when one or more ends have dropped. In a filter tow machine, for instance, a normal tow comprises 20 cabinet ends which, when crimped and processed, make up a cigarette filter of the proper density. If a cabinet end breaks out, corrective action must be taken to continue to produce the same unit density as before. If two cabinet ends break out, an additional correction may be made or perhaps all cabinet ends may be sent to waste until the down end or ends can be reinserted in the tow band. In any event, it may be preferable to provide some signaling agency to alert the operator that a cabinet end has become broken or missing.
In the prior art, for instance, a circular rod member is used to guide a cabinet end along a predetermined path. An air orifice is provided in the surface of the circular rod member with the circular member having an air passageway therein connected at one end to said orifice and being connected at the other end to a suitable air supply. As long as a cabinet end passes over the surface of the circular rod member, the cabinet end closes off the orifice and effectively prevents any bleed-off of air therefrom. When the cabinet end breaks or is missing for some reason, the orifice is no longer blocked and the bleed-off of air therefrom occurs at a rate faster than it can pass across a flow control valve, thereby activating a pressure switch and causing a signal to occur. One disadvantage of this arrangement is that the cabinet end usually has lubricant thereon and eventually the air orifice in the circular rod member becomes plugged with lubricant and debris to such extent that no air can bleed thereform when a cabinet end breaks or is otherwise missing.
An object of the invention, therefore, is to provide an ends-down sensor device in which the air orifice is protected from becoming plugged with yarn lubricant and debris.
U.S. Pat. No. 3,999,695 (1976) discloses a rotary sensor device for detecting a running filament end when the filament is passing over a rotatable cylinder. The rotary sensor device comprises a rotatable cylinder mounted for free rotation within a housing. The housing, which is stationary, has a fluid orifice. When a running filament is in frictional engagement with the rotatable cylinder, the frictional force causes the cylinder to be rotated to a limited extent, thereby overcoming and rotating a counterweight (in a manner not completely disclosed), which is normally blocking the fluid orifice when there is no filamentary yarn frictionally engaging the rotatable cylinder. Thus when the fluid orifice becomes unblocked upon the filament's engaging and rotating the rotatable cylinder, air is then allowed to flow from the orifice. When the filament breaks, the counterweight automatically rotates back into a position blocking the fluid orifice, thereby preventing the flow of fluid out of the orifice and causing a buildup of pressure to occur in the line through which the fluid passes to the orifice. The increase in pressure is sensed, as by using a diaphragm and an electrical switch in the manner shown in the patent. The economic consequence of this operation is that air is normally flowing from the orifice when the continuous filament is running against the rotatable cylinder. The consumption of air is costly. The fluid orifice is also in a position where it can be exposed to lint, dirt and lubricant that might be thrown off.
Another object of the invention is to reduce the amount of air that may be used in the operation of the sensor device.
Still another object of the invention is to provide a structure wherein the fluid orifice is protected from exposure to lint, dirt and lubricant.
Other objects inherent in the nature of the invention disclosed will become apparent to those skilled in the art from the description which follows.